Diamond Creek is a suburb of Melbourne, Victoria, Australia, 23 km north-east of Melbourne's Central Business District, located within the Shire of Nillumbik local government area. Diamond Creek recorded a population of 12,503 at the 2021 census.

There are two ideas about where Diamond Creek got its name. Victoria's Register of Geographic Names says that it was because of the way the stones glistened in the creek water. Local legend says it is because of a bull who was trying to cross a creek. The bull had a diamond shaped white patch on its head and found difficulty crossing the creek. Thus the Bullocky named the town after the bull with the diamond shape on its head and the creek it drowned in.

The Ellis family were pioneers of the District and benefactors of the Nillumbik cemetery gateway. Ellis Cottage, a rubble-stone hipped roof cottage contains its original fabric and is considered historically significant and is on the Victorian Heritage database.

Gold was first discovered in Diamond Creek in 1863 by Messrs Peers, Haley and Wilson. The Diamond Creek mine was opened some years after gold was first discovered and dug 700 feet vertical and 300 feet underlay. The value of gold taken from the mine was reported to be between £1,000,000 and £2,000,000 Australian at the time.

In 1867, the Nillumbik cemetery at Diamond Creek was established. It occupies an area of two acres between Main and Edinburgh Streets and is positioned on high ground above Sawpit Creek and the Diamond Creek floodplain. It is laid out in a grid formation. A brick and rendered archway was built in 1897. The cemetery is considered significant and is listed on the Victorian heritage database.

From 1894 to 1969 there were a number of bushfires. In 1894, houses and stock were destroyed.

In the postwar years, population increased dramatically in Diamond Creek and its neighbouring areas. The Diamond Valley Shire was created out of the northern part of the Shire of Heidelberg in 1964. Further population growth occurred throughout the 1970s. The early 20th century saw a decline in the orchard industry, as orchards in Melbourne's eastern townships such as Doncaster and Nunawading, fell into favour due to better marketing. Diamond Creek remained relatively untouched during the boom in recreational travel that followed the popularity of the motor car. ^{[citation needed]}

Diamond Creek was home to a Donkey Shelter from 1997 to 2012, which provided accommodation and care for neglected donkeys from around the state of Victoria. In 2012, this moved to Tongala.